can "reset to defaults" be hooked into?

[sharvell-collegeboard]

Is there a way to also execute custom code when the user selects the "Reset to Defaults" menu item?

[dpvc]

Here is a configuration that you can use to hook into the reset menu:

MathJax = {
  startup: {
    ready() {
      MathJax.startup.defaultReady();
      const reset = MathJax.startup.document.menu.menu.find('Reset');
      reset.registerCallback((item) => {
        // your actions here ("item" will just be the same as "reset" in this case)
      });
    }
  }
};

This will run after all the other items that have been registered.

[jmegginson]

Should the (default) behavior of "reset to default" be the same for version 4 as it is w/ v3? For 3.2.2 activating reset to default has always been the cleanest and quickest way to provide the default (hidden) MathML. I observe that with version 4, resetting to default enables many (other accessibility) features and actually removes the hidden MathML.

[dpvc]

Should the (default) behavior of "reset to default" be the same for version 4 as it is w/ v3?

It is the same. It resets the menu settings to the default settings for the page, which are the defaults set by MathJax as modified by the page author's configuration. The defaults for some menu settings are different in v4 than in v3, so that is whey there reset goes to different values.

If you want the default values to be those from v3, you need to set them that way in the MathJax configuration using the options.menuOptions.settings block. Whatever you set there will become the new defaults, so if you want the hidden MathML to be enabled and the other assistive tools disabled, then use

MathJax = {
  options: {
    menuOptions: {
      settings: {
        assistiveMml: true,
        enrich: false
      }
    }
  }
}

so that the reset-to-defaults item will turn off the explorer and turn on the hidden MathML.